Changing the size of display equation locally

Question

I want to increase the size of a display equation and only the equation.

The code in question is the following:

\begin{equation}
    \int_{0}^{n}x^2
    \label{eq:int}
\end{equation}

I have tried \begingroup

Normal equation
\begin{equation}
    \int_{0}^{n}x^2
    \label{eq:int1}
\end{equation}
Large equation
\begingroup
\Large
\begin{equation}
    \int_{0}^{n}x^2
    \label{eq:int2}
\end{equation}
\endgroup

but that also increases the size of the numbering.

And \scalebox doesn't properly work with things like \int:

\begin{equation}
    \scalebox{1.5}{
    $\int_{0}^{n}x^2$}
    \label{eq:int}
\end{equation}

So I'm looking for a way to get the size of the \Large display equation but a normal numbering. Also, I would need a way to reference the equations (with\ref) and I only want sizes to change on a case by case basis, so \DeclareMathSizes wouldn't really work.

Answer 1

You can use the relsize package, which has a \mathlarger{} command. You should see its manual for details; the manual also cautions against using it too broadly. (Below I used it twice, which means it should be the same size as what you get from \Large.)

Note also that the \scalebox solution should work also. If I am parsing you correctly you are just missing \displaystyle

\documentclass[11pt]{report}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{relsize}
\begin{document}
Normal equation
\begin{equation}
    \int_{0}^{n}x^2
    \label{eq:int1}
\end{equation}
Large equation
\begin{equation}
    \mathlarger{\mathlarger{\int_0^n x^2}}
\end{equation}
\Large
[ \int_0^n x^2 ]
\normalsize
\begin{equation}
    \scalebox{1.4}{$\displaystyle\int_{0}^{n}x^2$}
    \label{eq:int}
\end{equation}
\end{document}